1. Field of the Invention
The present invention relates to an object (a product including a machine, a manufacture, and a composition of matter) and a method (a process including a simple method and a production method). Specifically, one embodiment of the present invention relates to a power storage system, a power storage device, a semiconductor device, a display device, a light-emitting device, or another electrical device or a manufacturing method thereof. In particular, one embodiment of the present invention relates to a power storage system, a power storage device, a semiconductor device, a display device, a light-emitting device, or another electrical device which includes an oxide semiconductor, or a manufacturing method thereof.
2. Description of the Related Art
In recent years, a variety of electrical devices, such as portable terminals (typified by mobile phones and smartphones), electric power tools, and electric vehicles, are equipped with power storage devices.
A power storage device includes a secondary battery, such as a lithium ion battery, which can be repeatedly used by accumulation of electricity by charging.
In an electrical device equipped with such a power storage device, the power storage device can be charged by a power feeding device connected to the electrical device, for example (e.g., Patent Document 1).
Moreover, in an electrical device equipped with such a power storage device, power is supplied from a power feeding device wirelessly, so that the power storage device can be charged even without being physically connected to the power feeding device (e.g., Patent Document 2). Patent Document 2 discloses, as examples of such a power feeding method, an electromagnetic induction method and a magnetic field resonance method.
In the case of using the power feeding methods disclosed in Patent Documents 1 and 2, a power storage device can be charged by a power feeding device that matches the specifications of the power storage device.